Amateur scouts could easily envision an 18-year-old Zack Wheeler missing bats in pro ball when they watched the senior righthander pitch for his high school team in Dallas, Ga., about 30 miles northwest of Atlanta.

He had now stuff even back then, including steady low- to mid-90s velocity, the ability to spin a breaking ball and all sorts of projection in his lanky 6-foot-4 frame. Picking sixth in the 2009 draft, the Giants took Wheeler off the board immediately following the Orioles' selection of Matt Hobgood, the first prep righty drafted that year.

"It wasn't a hard pick for us," said Sean O'Connor, the area scout who worked the Southeast for San Francisco at the time. "Sometimes you get criticized for taking a high school righthander in the first round, but all the higher-ups had seen (Wheeler) pitch and liked him a great deal."

While scouts were right about Wheeler's potential—he reached Double-A this season and has thrived, earning the 22-year-old a second Futures Game invitation—they did not foresee the control problems that plagued him early in his career. Through his first 135 pro innings, Wheeler walked 83 batters—or 5.5 every nine frames—before his control improved dramatically and suddenly last July when a series of changes reshaped his future.

One of those changes transplanted him from San Jose to Port St. Lucie, Fla., when he switched high Class A clubs following a trade to the Mets, who sent Carlos Beltran to the defending World Series-champion Giants. A second change affected Wheeler in a much more fundamental way.

"About two bullpen (sessions) before I got traded, (Giants vice president of player personnel) Dick Tidrow watched me and told me to bring my leg up a bit, which meant I had to bring my hands up too," Wheeler said.

"He told me to go back to the way I threw in high school. 'You were one of the best high school pitchers I've ever seen,' he said. But in my first instructional league, (Giants coaches) slowed me down to be like everybody else—but not everybody else is tall and lanky like me."

Seldom do results manifest so quickly after a mechanical change. Wheeler walked only one batter in each of his final two starts for San Jose, on July 16 and 22. Following the trade, he walked five batters in six starts for St. Lucie. He has continued finding the strike zone this season with Binghamton, having issued 32 walks and allowed 51 hits through 79 innings. In fact, Wheeler has shaved his walk rate to an even 3.0 per nine innings since that fateful bullpen session—that's 39 free passes in 117 frames.

Tools For The Trade

Binghamton pitching coach Glenn Abbott notes that Wheeler has done well this season to keep his weight back and resist the temptation to rush his delivery. Like many scouts and coaches, Abbott believes that mastering body control as one approaches physical maturity can be the final obstacle for young pitchers—particularly those with long limbs, like Wheeler—on their way to developing big league command.

"I see a big difference in command between now and spring training," Abbott said. "He's still just a young guy learning how his body works, but he really hasn't walked a lot of guys. It's remarkable that for guy with the power stuff he has, he doesn't work a lot of deep counts. He lets opponents put the ball in play—or he throws it by them."

Wheeler's results in the first half back up Abbott's claim. Just six minor league starters had allowed a lower opponent average than Wheeler's .188. He ranked third in the Eastern League in both ERA (2.29) and strikeout rate among starters (8.8 per nine innings) while ranking fourth with a 1.06 WHIP. He had allowed only one home run in 13 starts.

Most of the credit goes to Wheeler's fastball, according to Abbott.

"I've been in this game 42 years and he's got as good a fastball as I've seen," the pitching coach and 11-year big league veteran said. "He sits 95-97 (mph), but it plays up to 100. Lots of guys throw hard, but their fastballs don't play that hard.

"Zack is the first pitcher I've seen in this league where hitters take defensive swings in hitter's counts off his fastball. He's got that late, explosive fastball you don't see often. He's got a chance to be an elite pitcher."

Wheeler relies on a four-seam fastball but occasionally will unveil a two-seamer that features sideways run away from lefthanded batters when he stays on top of the pitch.

However, the biggest difference between Wheeler three years ago and Wheeler today is an expanded repertoire that now includes a changeup and a slider. He said his slider developed from a cutter he began throwing in 2011 to combat lefthanded batters in the California League, where hanging curveballs and elevated fastballs can result in pop flies, which can result in home runs in many of the league's distinctly power-friendly parks.

The slider has found its way into Wheeler's heavy rotation this season because, as Abbott notes, it's easier to command than the curveball. "My slider was my second best pitch coming into this year," Wheeler said, "and when I throw it just right it looks like a fastball coming in."

While Cal League lefties lit up Wheeler for a .292 average and a .487 slugging percentage in 113 at-bats last year, those corresponding numbers by Eastern League lefties this year were .182 and .273 in 110 at-bats, thanks largely to an improved slider.

Generally, Wheeler said he just goes with whichever breaking ball is working for him that day. If his mid-80s slider is flat, he'll throw more curves. If he finds himself getting out too quick and casting his curveball, then he'll lean on his slider.

A Change Of Pace

Wheeler said he learned the value of the changeup during his first instructional league camp in 2009, and he's been trying to find a grip that works for him ever since.

"I didn't throw (a changeup) in high school, and I never really worked on one with the Giants," he said. "But we used to play the A's all the time in spring training and instrux, and with every pitcher they had, their second best pitch was a changeup. When they got the batter 0-2, they'd always throw a changeup."

Fittingly, the Mets hired former Oakland big league pitching coach Ron Romanik as pitching coordinator last offseason, and Wheeler said that Romanik has instilled the value of the change-of-pace in all the system's pitchers.

"Mine is a circle-change grip," Wheeler said, "but I just move my fingers up over the ball a bit and put my pinky under it to try to get depth. My changeup velocity is in the high 80s, and while that's enough difference for now, slower would be better."

Abbott stresses the value of the pitch and wants to see at least eight to 10 changeups out of Wheeler's hand in each start. Finding time to work on feel for the pitch can be a challenge, however, because he suffers from a middle-fingernail avulsion on his pitching hand, which means that the nail tends to disconnect from the skin underneath. Wheeler feels fine on days he pitches, but soreness often lingers into his side sessions between starts.

The persistent fingernail issue first cropped up in 2010 and landed Wheeler on the disabled list for the middle third of his pro debut season. He learned to navigate a professional workload and manage the avulsion in 2011, nearly doubling his innings total to 115. He missed a start in early May this season but returned at full strength afterward, and from May 17 to June 7 he reeled off four spectacular starts in a row, going 4-0, 1.24 with 30 strikeouts, 10 walks and nine hits allowed over 29 innings.

O'Connor, who now works as Southeast crosschecker for the Mariners, recalls that the Wheeler family was unusually prepared for the draft process, probably because Zack's older brother Adam, a righthander who topped out in low Class A, had been selected by the Yankees in the 13th round in 2001.

"Zack wasn't about going to college," O'Connor said. "He knew what he wanted to do. There wasn't a lot of talk about money, and very little about college. His decision was: I'm playing pro baseball. His focus was on getting better."

A rival Georgia area scout backs up that assessment. "It's rare for a high school kid to not get caught up in the hype and remain focused," the scout said. "But the makeup Zack brought to table was a big attraction. He didn't allow the money or the peripheral stuff to alter the way he approached the game. Whatever that secret ingredient is, this guy had it, and it gave you hope that as scouts we're making the right evaluations on these guys."